1. Field of the Invention
The present invention relates to a linear guide used in, for example, a machine tool, an industrial machine field or the like.
2. Description of the Related Art
There is known a linear guide of this kind of a related art as shown in, for example, FIG. 35.
The linear guide is provided with a guide rail 1 extending in an axial direction and a slider 2 being laid across the guide rail 1 so as to relatively move along the axial direction. Two side faces in a width direction of the guide rail 1 are formed with rolling element rolling grooves 3 respectively extended in the axial direction by two upper and two lower streaks thereof on one side, that is, four streaks in total, and a slider main body 2A of the slider 2 is formed with rolling element rolling grooves 5 respectively opposed to the rolling element rolling grooves 3 at inner side faces of two sleeve portions 4 thereof. A number of rollers 6 as rolling elements are rollably charged between the two rolling element rolling grooves 3, 5 and the slider 2 is made to be able to move on the guide rail 1 relatively along the axial direction through rolling movement of the rollers 6.
In accordance with the movement, the rollers 6 interposed between the guide rail 1 and the slider 2 are rolled to move to end portions in the axial direction of the slider 2 and in order to continuously move the slider 2 in the axial direction, it is necessary to infinitely circulate the rollers 6. For that purpose, there are formed two upper and two lower (a total of four) of holes 7 penetrated respectively in the axial direction into the sleeve portions 4 on both sides of the slider main body 2A and the holes 7 are inserted with circulation sleeves 8 whose inner portions form passages (rolling element passages) of the rollers 6, two ends in the axial direction of the slider main body 2A are fixed with a pair of end cap 9 respectively functioning rolling element circulating parts by screws or the like, and the end caps 9 are formed with direction changing passages 9a (referred to FIG. 3 and FIG. 4) curved in a shape of a semicircular arc for communicating intervals between the two rolling element rolling grooves 3, 5 and the rolling element passages 8a to thereby form infinite circulation tracks of the rollers 6.
The direction changing passages 9a provided at the end cap 9 for communicating the rolling element passages 8a on an upper side and the intervals between the two rolling element rolling grooves 3, 5 on a lower side and the direction changing passages 9a for communicating the rolling element passages 8a on a lower side and the intervals between the two rolling element rolling grooves 3, 5 on an upper side are formed to intersect such that the direction changing passages 9a do not interfere with each other. Meanwhile, in fixing the end cap 9 to the end face of the slider main body 2A, positioning of the circulation sleeve 8 (rolling element passage 8a) on a side of the slider main body 2A and the direction changing passage 9a on a side of the end cap 9 becomes important in ensuring smooth circulation of the rollers 6.
There is proposed a technology with regard to positioning in this way, in which, for example, two ends of a sleeve (circulation tube) are formed with chipped wall portions in a shape of a chipped circle, opening ends of direction changing passages of side plates (end caps) are formed with projected portions coinciding with the chipped wall portions of the sleeve, and the projected portions are fitted to insides of circular holes (inserting holes of the sleeve) of a casing (slider main body) and the chipped wall portions of the sleeve to thereby position the casing and the sleeves and the side plates each other (for example, refer to Japanese Patent Publication No. 2865854).
In this case, the casing, the sleeve and the side plate are constituted by separate members. Therefore, in integrating the sleeve, one end face of the casing is attached with the side plate, the sleeve is inserted into the circular hole penetrated to the casing from other end face thereof, and at that occasion, a phase is matched such that a shape of an inner periphery of the sleeve and a shape of an opening end of the direction changing passage of the side plate coincide with each other.
Japanese Patent Publication No. 2865854, JP-A-5-209617 and JP-A-9-72335 are referred to as related arts.
However, according to Japanese Patent Publication No. 2865854, when positioning of connecting portions of the circulation sleeve (rolling element passage) and the direction changing passage on the side of the end cap is going to be carried out accurately in order to make circulation of rollers smooth, it is necessary to promote an accuracy of fitting together the projected portion and the chipped wall portion. Therefore, unless the phase of the circulation sleeve is matched accurately, the end cap and the circulation sleeve are not integrated. Therefore, in inserting the circulation sleeve into the hole of the slider main body, the phase of the circulation sleeve needs to match accurately. In this case, operability is deteriorated and time is taken in integrating operation, which amounts to an increase in cost.
Further, in Japanese Patent Publication No. 2865854, the chipped wall portion provided at the circulation sleeve and the projected portion provided at the end cap are fitted together only at one location. Therefore, when the circulation sleeve is shifted by play by a clearance at the fitting portion, there is a concern that positioning of the rolling element passage in the circulation sleeve and the direction changing passage on the side of the end cap is not carried out accurately.
Further, it is difficult to determine the phase in a peripheral direction of the circulation sleeve at a glance and there is a concern of attaching the circulation sleeve to the hole of the slider main body by shifting the phase of the circulation sleeve by 180°. In this case, the chipped wall portion of the end portion of the circulation sleeve and the projected portion on the side of the opening end of the direction changing passage of the side plate (end cap) cannot be fitted together. Therefore, the integration cannot be carried out. Therefore, it is necessary to draw the circulation sleeve temporarily from the hole of the slider main body and reattach the circulation sleeve thereto by making the phase of the circulation sleeve correct again.
In this way, when the circulation sleeve is attached to the hole of the slider main body, it is necessary to pay close attention such that the direction of the circulation sleeve is not mistaken and integrating operation becomes complicated.
Further, in the case of the linear guide of the related art explained in reference to FIG. 35, when a circular arc track of a direction changing passage 10 provided at the end cap 9 and a linear track of the rolling element passage 8a in the circulation sleeve 8 are connected, since normally, the end cap 9 and the circulation sleeve 8 are die molded products of resin, a corner portion is provided with facing to prevent burr from being produced in molding or in using at the corner portion. Particularly, when facing 11 is provided at a part of an inner peripheral guide face 10a of the direction changing passage 10 connected with the rolling element passage 8a, as shown by FIG. 36, even when the end cap 9 is positioned to a regular position with respect to the circulation sleeve 8, a stepped difference is brought about at the facing portion 11. In this case, smooth circulation of the roller 6 is hampered and the operability is deteriorated.